The present invention relates generally to improvements in vehicle safety belt retractor devices and it relates more particularly to an improved vehicle safety belt retractor which is automatically locked against belt extraction in response to the vehicle acceleration, positive or negative, exceeding a given value.
The conventional acceleration responsive automatic locking belt retractor reel generally employs a highly sensitive acceleration sensing device which responds to transients experienced in many normal driving conditions so that the reel locking and releasing operation occurs with very great frequency thereby incurring many problems as will be hereinafter explained.
In a reel locking mechanism wherein extraction of the safety belt reel is locked by the engagement of a ratchet wheel by a pawl, it often occurs that the tip or tooth top of the pawl and the tip or top of a ratchet wheel tooth are concurrently advanced to an identical position so that the ratchet wheel tooth whose speed is greatly enhanced by the ratchet wheel which is rotated by the extraction force of the safety belt outwardly pushes the pawl tip thereby preventing the locking engagement of the ratchet wheel by the pawl. A considerable interval thereafter occurs during which the normal operation of the pawl in engaging the ratchet wheel is disabled. During this interval a considerable length of safety belt can be extracted from the retractor reel thereby nullifying the effectiveness of the safety belt.
Moreover, with the frequently repeated operation described above the retractor device becomes damaged and highly unreliable by reason of the damage and rupture of the pawl and ratchet wheel teeth tips so that proper locking engagement is no longer assured.